Coking high volatile coal



Patented July 18, 1944 Carl Otto, Manhasset, N.

Y.,-assignor to Fuel Refining Corporation New York, N. Y., a corporationof Delaware No Drawing. Application December 2, 1941. Serial No. 421,368

Claims. (01. 202-33) The general object of th present invention is toprovide a simple and effective method of producing a relatively strongand dense coke from coal having a volatile content of from forty tosixty percent, which is too high' to permit its 5 conversion into suchcoke by the customary methods used in the production of metallurgicalcoke. At the present time, practically all of the metallurgical cokeused in the world is made in byproduct coke ovens of the horizontalregenerative type, and is made from a coal, or a coal mixture, having avolatile content which is seldom higher than thirty-five percent andusually is about twenty-five to thirty percent, and which is heated l6to a final temperature of the order of 1800 F. or

higher. The volatile content percentages stated herein, are based oncoal free from its actual moisture and ash contents.

'My present invention was especially devised for, and is well adaptedforuse in coking so.- called Illinois coals, having a volatile contentin the neighborhood of forty-five percent, of which great quantities areavailable in this country for mining at a relatively low cost. When sucha when coked will contain seven pounds of ash will also containtwenty-eight pounds of carbon and.

coal is treated in a byproduct coke oven of standard type, in accordancewith the standard procedure followed in the production of metallurgicalcoke, the solid residue remaining after forty-five percent or so of theweight of the charge has passed away from the ovens in gas or vaporform, is in the form of coke, which is too porous and friable forpractical use.

I have discovered, however, that a relatively strong and dense coke canbe made from Illinois and analogous high volatile coals by a processcomprising the following steps. The formation of a moist carbonaceousmass having a water content of from ten to fourteen percent and which inmost cases is preferably about twelve percent of the weight of the coalincluding its ash content, and a carbonaceous content consisting whollyof light'volatile coal in a finely subdivided state or, and preferablyin many cases,

of such finely divided high volatile coal 'in ad- (5 mixture with fromtwo to five percent by volume coke in a subdivided state; the stampingor compression of the moist mass into compressed bodies adapted forinsertion in coking chambers, and

of such density that the weight of the non-volatile portion includingthe ash, of each body is approximately as great as that of a similarvolume of metallurgical coke; the insertion of the compressed bodies incoking chambers and the heating of the coking chambers to temperaturessimilar to or slightly higher than the oven temperatures used in thestandard production of -metallurgical coke. In order that the chargesome cases the oven width may'well be about thirteen inches.

In producing metallurgical coke from a good coking coal, in an ovencharged through openings in its top wall, the dry coal density of thecoal charge in the oven will normally be about .75 and with a normalaverage volatile content, the coke produced will weigh about thirty-fivepounds per cubic foot of charge, and in proceeding in accordance withthe present invention, I consider it ordinarily desirable to so compressthe coking charges, that the coke produced will weigh from thirty-threeto thirty-eight pounds per cubic foot of charge. In general, the weightof a charge produced in accordance with the present invention will begreater when the ash content of the coal is relatively high than when itis relatively low. For example, a charge of such composition that aportion thereof which of 1, so that the compressed charge will weighsixty-two and four-tenths pounds per cubic foot,

. and the coke formed with then weigh thirty-five pounds per cubic foot.Such coke maybe expected to have a density and mechanical strengthapproximately the same as that of good metallurgical coke. It ispractically feasible, when conditions make it desirable, to compress thecoal to a density appreciably higher than unity, for example to adensity of 1.05.

In the preferred practical mode of carrying out the invention, I firstbreak the coal into such relatively coarse particles that, after beingcleaned by any usual or suitable washing process, the coal mass willhold the ten to fourteen percent moisture content needed in thecompressed charge forming cake or body. After washing or otherwisewetting the coarsely subdivided coal, I subject it to a breaker orgrinding action to subdivide the coal so finely that abouteighty'perinch and adapted to pass particles about two' millimeters indiameter. I next compress the tomary in forming comp moist coal into acake or body suitable for chargprior to the formation of the enough sothirty mesh screen, i. e.

and advantageously, in some cases, the coke forty mesh screen, i. e. ascreen hundred openings per square inch. cake or body or coal so-calledhigh temperature carbonization of coal metallurgical coke. In such highcarbonization, the final coke temperature is of the order of 1800 F.whereas in the so-called low temperature carbonization of coal, thefinal coke, or char," temperature is of the order of 1000 F. Ordinarilyeach compressed cakeis made of proper size to form the entire charge ofa coking chamber. However, in some cases, it may\be desirable tocompress the coal into briquette-like bodies and to form each ovencharge of a stack of said bodies.

The compression of the charge may be effected by the use of chargestamping, or compressing, apparatus of various known forms of apparatusdevised for use in forming compressed coal cakes to be charged intocoking chambers, provided such apparatus has, or is given suiilcientstrength and power to efiect the compression required for thcimrposes ofthe present invention, which is appreciably higher than heretofore custoproduce temperature the purposes of coal density of the compressedcharge will normally be appreciably above be 1 or greaiigwhereasheretofore, the dry coal density of s ped coal charges has or y beenbelow .95, and usually about .9. I

Heretofore it has been assumed that a stamped or. compressed oven coalcharge should not have a height greater than the use of wider ovens withstamped coal charges than would otherwise be desirable. The greaterdensity of a coal charge cake formed in accordance with the presentinvention, results in increased strength of the cake and permits theheight to width ratio to be substantially greater than '7 to 1. In somecases the compressed charge bodies may be str ened and their cokingproperties improved, by adding pitch to the coal either by mixing it infinely ground form with the coal, or by spraying liquid pitch onto thecoal and then subjecting the coal to a mixin action prior to the cakeforming operation.

A coal charge forme compressed .and coked in accordance with the presentinvention, does not swell, and ordinari y does not deform during thecoking operation so that the taper in the oven chamber wid which ischaracteristic of the standard type ovens, is not needed, but on thecontraryris un esirable in the'practice of my invention. U

.The coking portion of my improved process may well be carried out inregenerative coke ovens differing from those of standard type only inthe omission of oven taper,

nine hundred openings per square ressed coal charges. For the presentinvention, the dry' or, and prefer- In my copending trial and the largefacture of metallurgical, and'also jected to the full customary instandard byproduct metallurgical 'coke oven plants. A practicaleconomical ad- In such a low cost plant, the distillation gasesy beused, pa y i ing the coke oven hattery and partly in firing steamgenerating boilers included in the plant for power purposes, and wasteheat boilers may also be heated, or other industrial heating purposesserved, by the waste heating gases passing away from the coke ovenbattery.

The fact that the compressed coal charges do not swell or deform duringthe coking operation, permits the walls between the heating fines andthe coking chambers to be reduced I without making the heating wallsundesirably weak, and thereby permits the rate of heat transfer to thecharge and the final coking temperature to be higher than is customaryin the production ofv metallurgical coke with the same flue temperaturescustomarily employed n th n making up for some of the loss in thermalefliciency theoreticslly resulting from the non-use of regenerators.application for patent, Serial No. 330,049, iiled April 1'1, 1940, Ihave disclosed and claimed a relatively simple and inexpensive wasteheat coke oven especially devised and adapted for use inthe practice ofmy improved process, but further references therein are unnecessary inview of the fact that the present other types and forms.

' By proceeding in accordance with the present invention, it is pombleto produce from high volatile coal a coke strong enough to withstandhandling and transportation, with little if any 'greater formation ofbreeze, than is produced a similar handling and transportation ofordinary metallurgical coke.

rocess forms an excellent fuel, and because of its density and strengthburns on a grate or in a fuel bed about as does ordinary metallurgicalcoke, and is a satisfactory substitute for the latter for domesticpurposes and for many indus- The addition to the high volatile coal offrom two to five percent of suitably sube e iii,

byproduct recovery treatment distillation gases evolved, to

inthickness' the manufacture of metallur ical The coke producedbydivided coke adds to the mechanical strength of and improves the cokeproduced.

This application is acontinuation in part of my prior patent applicationSerial No. 330,048, filed April 17, 1940.

While in accordance with the provisions of the statutes, I haveillustrated and described the best forms of embodiment of my inventionnow known to me, it will be apparent to those skilled in the art thatchanges may be made in the form of the apparatus disclosed withoutdeparting from the spirit of my invention as set forth in the appendedclaims invention may be used to advantage without a corresponding use ofother features. l

Having now described my invention, what I claim as new and desire tosecure by Letters Patent, is:

1. The method density and strength to metallurgical coke; from 2. Amethod as specified in claim 1, in which the high volatile coal is mixedwith from two to five percent of coke subdivided so finely that and thatin some cases substantially all or it will pass a thirty mesh per inchscreen.

3. A method heat is high at 1800 F.

4. The method'of producing a. relatively strong and dense coke from coal'5. The method of producing a relatively strong and dense coke from coalhaving a volatile content of forty or more percent, which consists inabout eighty per cent content weight or from thirtythree to thirty-eightpounds then coking said body in a retort in which said

